With DC motors used for hermetic electric compressors, protection against overcurrent and abnormal temperature has been provided on the control side (inverter or software). However, recently, it has been pointed out that protection by software only is insufficient, and there is a tendency for mandatorily installing mechanical protection devices. Therefore, hermetic electric compressors are provided together with mechanical protection devices known as internal protectors. Such an internal protector, as described in, for example, Patent Literature 1, opens a contact of a bi-metal switch by detecting an overcurrent or abnormal temperature when a current or temperature exceeds a reference value and protects the electric motor from fire damage, etc. by interrupting the electric circuit.
In addition, the above-described internal protector, as described in, for example, Patent Literatures 2 and 3, is often installed at an end of a stator of an electric motor. A common procedure has been to fix the internal protector onto the stator winding wire of the electric motor, either directly or covered with an insulating sleeve, by tying it with a tying cord or the like used when forming the stator winding wire.